Concrete-form.



J. W. HUNTER.

CONCRETE FORM. APPLIoATIon PILEJULY 21. 1913.

Patented Dec. 22, 1914.

2 annua-SHEET 1.

J. W. HUNTER.

CONCRETE FORM.

APPLIUATION FILED JULY 21, 1913.

1,1 21,840. Patented Dec. 22, 1914.

2l SHEETS-SHEET 2.

- WITNESSES: INVEN'IOR.'

ATTOR NE Y.

THE MORRIS PETERS C0.. PHOTo-LfTr-lo.. WASHlNcrON, D. C,

JOI-1N W. HUNTER, OF ENGLEl/VOOD, MISSDURI.

CONCRETE-FORM.

Specification of Letters Patent.

Patented Dec. 22, 1914;.

Application filed July 21, 1913. Serial No. 780,188.

To all 'whom it may concern Be it known that I, JOHN TW. HUNTER, a citizen of the United States, residing at Englewood, in the county of Jackson and State of Missouri, have invented certain new and useful improvements in Concrete- Forms, of which the following is a specification.

This invention relates to improvements in concrete forms for sewers, tile, silos and other structures of cylindrical or near cylindrical form, and my object is to provide a form of this character which can be manufactured at small cost and quickly set up for use, or taken down after such use.

ln order that the invention may be fully understood, reference will now be made to the accompanying drawings, in which:

Figure 1 is a broken longitudinal sectional view of the form in use in the construction of a sewer. Fig. 2 is a cross section enlarged, on line ll-H 'of Fig. 1. Fig. 3 is an elevation of a head-block employed in carrying out the invention. Fig. 1 is an elevation of an adjustable annulus constituting an important feature of the invention. Fig. 5 is an enlarged broken section of the annulus and gearing for adjust' ing the same. Fig. 6 is a cross section, enlarged, on line Vl-V1 of Fig. 4. Fig. 7 is a broken detail perspective of a resilient shell employed in carrying out the invention.

1 designates a sheil of cylindrical or substantially cylindrical form and split longitudinally as indicated at 2 to admit of being adjusted diametrically as hereinafter described. Shell 1 being resilient, automatically contracts to its smallest diameter when relieved of pressure, and is provided with a plurality of longitudinal slide-ways 3, which reinforce said shell and form a track for a companion shell or shells to be slid longitudinally through the first-mentioned shell as will hereinafter appear.

4 designates an annulus one end of which overlaps the other as shown on Fig. 5, and is provided with a rack-bar 5 intermeshing with a worm G fixed upon a shaft 7, journaled in a bearing 8 fixed to said other end of the annulus l which is, preferably, madeof channel-iron to obtain the requisite strength with the least weight. Both ends of shaft 7 are squared as indicated at 9 to receive a wrench or other tool whereby said shaft and the worm-wheel 6 are rotated to expand or contract the annulus 4f.

10 designates a head-block having a cir-` cular shoulder 11 to enter and hold one end of the shell 1 in expanded condition. Said head-block 10 is also provided with a peripheral flange 12 which acts as a gage in determining the thickness of the concrete to be applied to the exterior of the shell 1. Head-block 10 lis made in two sections, so that it may be expanded or contracted. Said sections have overlapping ends 13 provided with slots 1li to receive bolts' 15, which with nuts 16 lock the two sections of the head-block 10 together, after they have been adjusted as desired. i

17 designates a plurality of concrete piers which l nd convenient to employ as a, l

foundation when the mold is usedfinthe construction of a sewer.

1n constructing a sewer, l usually proceed as follows: A number of shells 1 are placed together with lapping ends as shown on Fig. 1. Said shells are laid upon the concrete piers 17 to which they are secured by any suitable means, such, forinstance as machine screws 18 which are passed through holes 19 in the shells and screwed into nuts 20, embedded in the piers 17, see Fig. 2. rl`he shells l are then expanded to the desired diameter through the intermediacy of one or more annuli t after which a head-block 10 is placed in each of the endmost shellsl.

rlhe concrete or other plastic mixtureA is then placed around 'the shells 1 and the piers 17, the thickness of the material being gaged by the peripheral flanges 12 of the two head blocks 10, above mentioned. fter the concrete has become set sui'liciently to support its own weight, the form is removed and another section of sewer laid.

One convenient way of removing the form is to allow one of the endmost shells 1 to contract by removing the head-block 10 and annulus 4: therefrom and drawing said shell through the remaining shells `on the slideways 3, in the direction in which the sewer is to continue. The remaining shells may successively be removed in a like manner. l/Vhile I have shown the preferred form of my invention, 1, of course, reserve the right to make such changes in the form and construction of parts as properly fall within the spirit and scope of the claims.

Having thus described my invention what I claim and desire to secure by Letters Patent is:

1. In a form of the character described,

a split shell, an adjustable one-piece annulus for expanding and bracing,y said shell, said annulus being independent of and removable from the shell, and gearing for adjusting; said annulus.

2. In a form of the character described, a split shell, an adjustable one-piece annu; lus for expanding and bracing said shell, said annulus being independent of and removable rom the shell, a rack-bar at one end of said annulus, and a worm mounted at the opposite end oi' said annulus intermeshing with the rack-bar.

3. A forni of the Character described, consisting of a split shell, an adjustable annulus to expand said shell, an adjustable headbloek having a substantially circular shoulder to it into either end of the split shell,

Copies on? this paient may be obtained for and a marginal flange on said head-block adapted to project beyond the periphery oi' the split shell.

4. ln a form of the character described, a headnblook of two sections having overlapping ends, means to adjustablv secure said ends together, a substantially circular shoulder on said bead-block, and a marginal flange on said head-block, extending' beyond the shoulder to act as a gage or molding surface.

lin testimony whereof l affix my signature, in the presence of two witnesses.

JOHN W. HUNTER.

TWitnesses:

K. M. lMBoDEN, L. J. FISCHER.

five cents each, by addressing the Commissioner oi Fatemi, Washington, 2D. C. 

